Method of and apparatus for trimming rubber heels



P 1942. c. s. KNIGHT 2,295,090

METHOD OF AND APPARATUS FOR TRIMMING RUBBER HEELS Filed March 20, 1941 2Sheets-Sheet l v INVENTOR M515 5;-

Q I ATTORNEY- 2 Sept. 8, 1942. c, s, KNlGHT 2,295,090 I METHOD OF ANDAPPARATUS FOR TRIMMING RUBBER HEELS Filed March 20, 1941 2 Sheets-Sheet2 INVENTOR M 5. l w

ATTORNEY.

Patented Sept. 8, 1942 METHOD OF AND APPARATUS FOR TRIMMING RUBBER HEELSChesterton S. Knight, Brockton, Mass., assignor to Geo. Knight & Co.,Brockton, Mass., a copartnership composed of George Knight, George R.Knight, Chesterton S. Knight, F. Stuart Knight, and Carlton E. KnightApplication March 20, 1941, Serial No. 384,334

9 Claims.

When a rubber heel is removed from the mold .cavity in which it has beenshaped and vulcanized,

it practically always has a fin or flange of rubber projecting laterallyfrom its upper edge and extending more or less completely around theheel. This, flange (commonly referred to as flash) is the overflow orsurplus stock which has been introduced in the mold in order to be surethat the cavity will be completely filled out. Some overflow necessarilyresults, varying somewhat in quantity with different heels produced inthe cavities of the same mold, and this surplus material must be trimmedoil before the heels are sold. Such a trimming operation is laboriousand naturally increases the manufacturing expense of the product.

The present invention is especially concerned with this flash trimmingoperation, and it aims to improve both the methods andv the apparatusused in this process with a view to accomplishing this result moreefliciently and economically. The nature of the invention will bereadily understood from. the following description when read inconnection with the accompanying drawings, and the novel features willbe particularly pointed out in the appended claims.

In th drawings:

Figure l is a-perspective view of a novel die structure which forms onefeature of this inventlon;

Fig. 2 is a vertical, sectional view of apparatus designed for use inperforming the method of this invention, this view being takenapproximately on the line 22, Fig. 3;

Fig. 3 is a front elevation of the parts shown in Fig. 2 but omittingthe roll;

Fig. 4 is a side view of a die structure similar to that shown in Fig. lbut difiering from it in respects later to be described;

Fig. 5 is a view similar to Fig. 2 and showing the parts in position todischarge the trimmed heel; and

Fig. 6 is a perspective view of a typical rubber heel before beingtrimmed.

Referring first to Fig. 6, a rubber heel as it is removed from a cavityof a heel mold after the molding operation has been completed is thereshown. It includes a heel body 2 of any suitable shape with the flangeor flash 3 projecting from its upper edge, as above described.

The mechanism provided by this invention for trimming ofi the flashincludes a die structure, a preferred form of which is illustrated inFig. 1. It comprises a cutting die 4 integral with a die plate 5, thecutting edge being raised substantially above the adjacent surface ofthe p This edge surrounds a heel-shaped aperture of such form anddimensions as to receive loosely the body portion 2 of the particularheel on which it is to operate. A die base 6 supports the plate 5, thetwo being secured together by screws, or'in any other convenient manner,and this base is made of U-shape or, in other words, is provided with along slot to receive rather loosely a plate 1 which forms the bottom forthe aperture in the die during the trimming operation.

In using this apparatus the heel to be trimmed such, for example, asthat shown in Fig. 6, is placed in the aperture of the die 4, the bottomplate at this time completely closing the lower side of the cavity sothat the heel can bottom on this plate. made of such dimensions as toleave a slight but substantially uniform clearance all around the heel,such a clearance being, say, in the neighborhood of twenty-thousandthsof an inch, in a typical instance. Also, the depth of the cavity shouldbe less than the maximum height of the heel by a slight amount whichwill vary somewhat with different heels but which can be readilydetermined after trimming two or three. Usually the body portion of theheel should project above the cutting edge 4 of the die by a distance ofperhaps a sixteenth of an inch, or thereabouts.

This assembly may then be placed in a press, or pressure may be appliedto the upper surface of the heel in any other convenient way serving tocompress the heel in its vertical dimension. The first result of thispressure is to expand the heel in practically all directions in its ownplane, and this expansion continues until the rubber body of the heelhas completely filled out the crosssectional dimensions ofthe die' 4adjacent to its upper edge. Further pressure will force the flash, whichat this time overlies the cutting edge, down upon said edge, thustrimming it of! substantially flush with the edges of the heel.

An. organization suitable for performing this pressing operation isillustrated in Figs. 2 and 3, in which the bottom plate I is shownmounted securely on the upper surface of the bed 8 of a press. Thecooperating platen is shown at'lll. Usually the bed is stationary andthe platen is reciprocated up and down by any convenient type ofmechanism. The so-called "perforating presses commonly used in the shoetrade are admirably adapted for this purpose. They are usually equippedwith a single revolution clutch so that when the operator steps on thetreadle the platen makes one stroke toward the bed, re-

The cavity or aperture should be turns to its initial position and stopsthere, and they also include means for adjusting the stroke of theplaten. In addition, such a machine customarily is provided with railsI2--l2 for supporting the die base 6 for sliding movement into and outof operative position in the press, and the die may have a handle l3secured thereto for the convenience of the operator in sliding the dieinto and out of the press.

The most convenient procedure is to place the heel 2 in the die whilethe latter is withdrawn, the heel at this time being supported by theflash resting on the cutting edge 4 of the die. The operator then pushesthe loaded die into the press. Because the over-all height of the dieplate 5 is less than that of the heel, some means must be provided tolift the'heel so that it can slide over the bottom plate 1 into such aposition as that shown in Fig. 2. For this purpose the rails l2l 2 aresupported on light springs 14-". Consequently, when the platen ldescends, it first strikes the upper surface of the untrimmed heel 2 andthe resistance of the flash to cutting is such, as compared to thestrength of the springs "-14, that the first action is to lower therails l2l2 with the die structure supported on them until the heelstrikes the upper surface of the bottom plate 1. Thereafter the heel iscompressed vertically, as above described, and then the flash is trimmedoff, the stroke of the platen In being so adjusted that it stops just asit meets the cutting edge 4 of the die.

When the platen rises the die is pulled out into some such position asthat shown in Fig. and

the trimmed heel 2 drops out of the die by gravity. The trimmed offsection 3 of flash is stripped ofi the die, a new heel is placed in it,and the operations above described are repeated.

It will be evident from the foregoing that heels may be trimmed inaccordance with this invention at a high rate of speed, with a highdegree of accuracy, and with relatively little effort and practically noskill on the part of the workman.

As the heel expands laterally under the pressure of the platen, there issome slip of its upper surface under the platen. It is desirable thatthis slip be made relatively free and frictionless so as not to impedethe lateral expansion of the rubber heel body. For this purpose alubricant of any suitable kind, such as talc or water, may be introducedbetween the meeting surfaces of the platen and heel. This operation maybe performed either by hand or automatically, and one convenientarrangement for applying a lubricant is illustrated in Fig. 2. Here aroll [5 is removably supported in two brackets, one of which is shown at16, so that as a heel is moved forward into the press its upper surfacewill engage the peripheral surface of the roll and rotate the latter,

thus coating the heel with water carried by the roll. If the body of theroll is made with a thick layer of sponge rubber, it will applysufflcient water to the heel for lubricating purposes and it will retaina considerable quantity of water. The supply of waterin the roll may bereplenished simply by dipping it in a container filled with the liquid,or water may be fed to the roll at a regulated rate by any convenientform of drip apparatus.

It is preferable to be able to adjust the height of the die plate sothat the degree to which the heel is compressed before the edge of thedie cuts into the flash can be adjusted to suit the requirements of aseries of individual heels. For

this purpose the die plate 5 may be made in upper 7 5 and lower sectionsa and b, as shown in Fig. 4, and these may be spaced apart by a seriesof shims c, all of these parts being secured releasably together bybolts or screws. Shims may be removed or inserted as required to adjustthe die to the desired over-all height.

While I have herein shown and described a typical embodiment of myinvention and a preferred way of carrying out the process, it will beevident that the method of this invention may be performed with the aidof a great variety of forms of apparatus, and that the invention may beembodied in other forms without departing from the spirit or scopethereof.

Having thus described my invention, what I desire to claim as new is:

1. That improvement in methods of trimming the flash on a molded rubberheel, comprising the steps of expanding the heel with the flash thereonin substantially all directions in the plane of the heel, and cuttingoff the flash substantially flush with the edges of the heel while it isso expanded.

2. That improvement in methods of trimming the flash on a molded rubberheel, comprising the steps of expanding the body of the heel intoengagement with the surface of an encircling wall confining the heel atits edges while leaving the flash projecting beyond said surface, andthen cutting oil the flash substantially flush with said surface.

3. That improvement in methods of trimming the flash on a molded rubberheel, comprising the steps of loosely enclosing the edges of the heelimmediately below the flash, compressing the heel vertically and therebyexpanding it willciently to cause it to fill the cross-sectionaldimensions of said enclosure immediately below the flash while leavingthe flash projecting beyond the enclosing surface, and then cutting offthe projecting flash.

4. A method according to preceding claim 3, including the steps ofrelieving the pressure on said heel after the flash has been cut off andthereby allowing the rubber body of the heel to contract, and permittingit to drop out of said enclosure.

5. That improvement in methods of trimming the flash on a molded rubberheel, comprising the steps of loosely enclosing the edges of the heelimmediately below the flash in a confining wall having a cutting edgesurrounding said heel edges immediately below the flash, compressing theheel vertically thereof and thereby expanding it laterally until itsubstantially fills out the space defined by said wall, andsimultaneously pressing the flash upon said edge and thereby cutting itoff.

6. In a mechanism for trimming the flash from a molded rubber heel, thecombination with a die having a cavity therein shaped to receive saidheel loosely, said die being provided with a cut.- ting edge surroundingsaid cavity, a base for said die, a bottom plate for said cavity servingas a support for a heel positioned therein, and means supporting saidplate and said base for relative sliding movement into and out ofcooperative relationship to each other.

7. In a mechanism for trimming the flash from a molded rubber heel, thecombination with a die having a cavity therein shaped to receive saidheel loosely, said die being provided with a cutting edge surroundingsaid cavity, a base for said die. a bottom plate for said cavity servingas a support for a heel positioned therein, one or more shims betweensaid die and said base, and means for releasably fastening said partstogether.

8. In a mechanism for trimming the flash from a molded rubber heel, thecombination with a die having a cavity therein shaped to receive saidheel loosely, said die being provided with a cutting edge surroundingsaid cavity, a base for said die, a bottom plate for said cavity servingas a support for a heel positioned therein, a bed supporting said bottomplate, a platen movable toward and from said bed into and out of contactwith a heel in said die, rails on which said die base is mounted formovement into and out of cooperative relationship to said bottom plate,and springs supporting said rails normally in an elevated position butyielding under the pressure of said platen on said die.

9. In a mechanism for trimming the flash from a molded rubber heel, thecombination with a die having a cavity therein shaped to receive saidheel loosely, said die being provided with a cutting edge surroundingsaid cavity, a base for said die, a bottom plate for said cavity servingas a support for a heel positioned therein, a platen movable toward andfrom said base to press the flash on the heel against the cutting edgeof said die, and means supporting said plate and said die for relativemovement to open the bottom of the die for the heel to drop therethroughand to close it again for operation on another heel. CHESTERTON S.KNIGHT.

